Brachytherapy Alone Versus Whole Breast Radiotherapy After Breast Conserving Surgery: 5-year Results of a Phase I-II Study and Interim Findings of a Phase III Trial

Reviewer: Roberto Santiago, MD
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Ultima Vez Modificado: 9 de octubre del 2002

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Presenter: Csaba Polgar
Presenter's Affiliation: Department of Radiotherapy, National Institute of Oncology, Budapest, Hungary
Type of Session: Scientific

Background

    Partial breast irradiation (PBI) has recently received alot of attention, especially since the FDA approval of a balloon-type brachytherapy applicator. This therapeutic approach is intended for highly selected patients with early invasive carcinoma of the breast with low-risk for local failure. There is limited data comparing the effectiveness of PBI to conventional BCT. This study tests the safety of PBI with interstitial HDR brachytherapy (HDR-BT) after breast conserving surgery (BCS) for T1 breast cancer in a phase I-II study, and to present the initial findings of a phase III trial comparing the efficacy of tumor bed irradiation (TBRT) alone with conventional whole breast radiotherapy (WBRT).

Materials and Methods

  • Forty-five prospectively selected patients with T1 N0-1a breast cancer undergoing BCS were enrolled into a phase I-II study of TBRT alone, using interstitial HDR implants.
  • HDR-BT consisting of seven fractions of 4.33 Gy (n = 8) or seven fractions of × 5.2 Gy given two per day (n = 37) was delivered to the tumor bed.
  • Based on the results of this phase I-II study, 222 additional patients were randomized to receive WBRT (50 Gy in fractions of 2 Gy) or TBRT alone.
  • Approximately 2/3 of the TBRT group consisted of patients treated with seven fractions of 5.2 Gy HDR-BT and 1/3 of patients treated with 50 Gy wide field electron irradiation in patients unsuitable for brachytherapy.
  • The eligibility criteria for both studies were: unifocal T1 disease, uninvolved margins of resection, no more than microscopic axillary node involvement, no grade 3 tumors, no in-situ carcinomas, no lobular carcinomas, and no EIC.
  • The two arms were well balanced.
  • Breast cancer related events and side effects were assessed. For late side effects only patients with a minimum follow-up of 20 months were evaluated.

Results

  • Phase I-II study: At a median follow-up of 66 months 2 (4.4%) local (all outside the tumor bed), 3 (6.7%) axillary, and 4 (8.9%) distant failures were observed. Three patients (6.7%) died of breast cancer.
  • Both local failures were salvaged with breast conserving surgery and whole breast radiotherapy.
  • The 6-year probability of cancer-specific (CSS), relapse-free (RFS) and local recurrence-free survival (LRFS) was 90.0%, 85.9% and 95.6%, respectively.
  • The cosmetic results were judged to be excellent in 44 out of 45 patients (97.8%). Severe (> G 2) skin sequalae or fibrosis was not found. Symptomatic fat necrosis occured in 2 (4.4%) patients.
  • Phase III study: At a median follow-up of 28 months, 1 patient in each arm has developed local recurrence, both of which were in the tumor bed. Both local failures were salvaged with breast conserving surgery and whole breast radiotherapy.
  • The 3-year probability of CSS, RFS and LRFS was 98%, 96% and 98% in the WBRT group and 100%, 94% and 98% in the TBRT group, respectively (p = NS).
  • There was no significant difference between the two treatment arms regarding the incidence of radiation side effects. There was one case of grade 3 fibrosis in the brachytherapy group. TBRT was significantly more cost effective than WBRT.
  • There was evidence of a learning curve for the brachytherapy procedure including the placement of more catheters per implant, bigger volume coverege by therapeutic doses, and better dose homogeneity as a function of time.

Author's Conclusions

  • Five-year results of our phase I-II study prove that sole HDR-BT of the tumor bed with careful patient selection and adequate quality assurance is a feasible alternative to WBRT.
  • At a median follow-up of 30 months in phase III study, HDR-BT alone is similar to WBRT with respect to skin and parenchymal side effects.

Clinical/Scientific Implications

    Longer follow-up is required to draw a final conclusion regarding the difference in local control rate between the two treatment arms. Promising early results support further accrual into ongoing trials of this and similar approaches. There is a learning curve associate with this techniques probably requiring special training. This could be a reasonable approach for highly selected patients with limited access to conventional BCT practices.

Oncolink's ASTRO Coverage made possible by an unrestricted Educational Grant from Ortho Biotech.


News
Strategy is alternative to whole breast radiotherapy delivered over several weeks

Jun 8, 2010 - In women ages 45 and older with early invasive breast cancer who are undergoing breast-conserving surgery, a single dose of targeted intraoperative radiotherapy may be as effective at preventing breast cancer recurrences as several weeks of conventional whole breast radiotherapy, according to a study published online June 5 in The Lancet to coincide with a presentation at the 46th Annual Meeting of the American Society of Clinical Oncology, held from June 4 to 8 in Chicago.


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